There are definitely some language problems here
The way to increase the working pressure in a J type is to shim or swap
the main central spring in the relief valve. John Kipping is correct,
the early "adjustable" PRV as described in most manuals, is a pain in
the backside and to be avoided. The later one, using what's known as the
"solid piston", is much easier to change/shim, but you do need to swap
the entire assembly. The later system was introduced in about 1975, but
was previously used by Laycock in race units. I have all the laycock
shim & spring data if anyone wants it.
The way to make it operate faster however, is to minimize the cone
clutch travel from free to engage (down to about 030" under a pressure
test), plus to drill out the control passage between the solenoid & main
oil circuit. This is called the "z passage" in most manuals.
Terry O'Beirne
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